Orthoses serve to correct malpositions of body parts such as e.g. arms, legs or the torso. For the purposes of producing an orthosis, a copy of the affected body part, for example a forearm, of the patient was previously manufactured by virtue of initially taking a plaster cast of the body part in the desired correction position. Thereupon, the orthosis contour was produced on the plaster model in a deep drawing or laminating process by virtue of a heated plastic plate being placed around the plaster model. Subsequently, the plastic was removed from the plaster form in a grinding workshop. Here, the inner plaster core was e.g. broken away by a hammer drill with a chisel attachment and the contour of the orthosis was cut out. After removing the inner core and approximately cutting out the spiral contour, the cut edges had to be post-processed by a number of grinding processes. This was carried out first by an approximate grinding process and then by final smoothing to form the intended contour. Furthermore, the inner surfaces were provided with an attached lining for increasing the comfort of wear. Thereupon, the orthosis could be matched to the forearm of the patient by a qualified orthopedist. Points at which there was increased pressure on the skin or edges that cut into the skin could subsequently be removed by polishing or by means of local heating.
However, this conventional production method has a number of disadvantages. The geometry of the model is, as a rule, over-dimensioned due to the plaster cast method, as a result of which an approximation to the original dimensions must be effectuated during the modeling. Further, there can be gross manufacturing inaccuracies as a result of the manual production, leading to an uneven contact face on the body part of the patient. As a result of this, local pressure points may arise on the skin which, over a relatively long period of time, are perceived to be particularly uncomfortable, up to a painful feeling.
Moreover, the described production process is complicated as it is hardly possible to resort to standard components. Each work step is undertaken manually, in particular as a result of the necessary, high individualization of the individual products and the relatively low number of units when compared with other industry sectors. This significantly increases both the production costs and the time outlay for the production. In parallel with this, the reproducibility of the individual measures is made more difficult.
Since the entire production process is carried out by hand, it is not possible to ensure a high surface accuracy. In particular, manufacturing the body part copy from plaster may cause significant form deviations of several millimeters. In the subsequent processing of this plaster copy, material is additionally removed and applied according to the empirical knowledge of the orthopedist in order to smooth the surface and rectify impression errors. In so doing, the original contour can only be reproduced approximately.
Moreover, an unchanging correction quality cannot be ensured during manufacturing. As a rule, the orthosis must be post-corrected again when it is tried on the patient. Moreover, it is not clear at the end of the manufacturing process whether the correction position that was set at the outset by the plaster cast could be accurately achieved.
Consequently, the main cause of the manufacturing tolerances that occur is, firstly, the practice of manufacturing the body part copy from plaster, which produces significant form deviations of several millimeters. Secondly, the subsequent processing steps should be assigned to the handiwork of the respective modeler, which has an effect on the comprehensible documentation and manufacturing quality.